Intra prediction method and device

3. The method of claim 2, wherein W2 equals to either 2*W or W+H, and wherein W represents a width of the current chroma block and H represents a height of the current chroma block.

5. The method of claim 4, wherein H2 equals to either 2*H or W+H, and wherein W represents a width of the current chroma block and H represents a height of the current chroma block.

8. The method of claim 1, wherein the down-sampled luma block of the luma block is obtained by down-sampling a reconstructed luma block of the luma block that corresponds to the current chroma block.

9. The method of claim 8, wherein only one row of neighboring reconstructed luma samples of the reconstructed luma block are used to obtain the luma reference samples when the luma reference samples are obtained based on only neighboring samples above the luma block and when a top row of the current chroma block is overlapped with a top row of a current coding tree unit (CTU).

16. The device of claim 15, wherein W2 equals to either 2*W or W+H, and wherein W represents a width of the current chroma block and H represents a height of the current chroma block.

18. The device of claim 17, wherein H2 equals to either 2*H or W+H, and wherein W represents a width of the current chroma block and H represents a height of the current chroma block.

21. The device of claim 14, wherein the down-sampled luma block of the luma block is obtained by down-sampling a reconstructed luma block of the luma block that corresponds to the current chroma block.

22. The device of claim 21, wherein only one row of neighboring reconstructed luma samples of the reconstructed luma block are used to obtain the luma reference samples when the luma reference samples are obtained based on only neighboring samples above the luma block and when a top row of the current chroma block is overlapped with a top row of a current coding tree unit (CTU).